Diagnostic Molecular Biology 4. Case Studyonngm A 38-year-old man required a bon
ID: 301704 • Letter: D
Question
Diagnostic Molecular Biology 4. Case Studyonngm A 38-year-old man required a bone marrow transplant due to a recent diagnosis of acute lymphocytic leukemia (ALL). Tests were performed to determine if either of the man's siblings, an older brother and a younger sister, were compatible with the patient and could serve as a bone marrow donor. For this case we are looking for a 100% match. The HLA haplotype of the man and that of his siblings was determined by sequence-specific PCR. A panel of primers that had specificity for particular HLA alleles was used to amplify DNA isolated from the three siblings. A second set of primers was added to each well as an amplification control. The table below summarizes the results in terms of the number of bands seen in each reaction well for each of the three people: Patient Brother Sister Allele A 3401 one A 1104 A"0302 A 2419 two one none A 2369 one onenone A 2610 one two none | two lone A 2601 A 3103 B*3906 8*5307 B 3919 B 3501 B0804 two B5603one one none one one one one one two none DR81 0422 one onenone DRB1 1411 one two DR81 081 two one DRB1 1317 one DR81 1117 two two oe a) Explain what a haplotype is and if they are always shared by siblings b) What is the HLA haplotype of each of the three people involved in this case? c) Are either of the patient's siblings a match? If yes, which sibling? d) Are all of the results acceptable? What could explain an incomplete or inaccurate result?Explanation / Answer
A) A haplotype is a group of genes within an organism that was inherited together from a single parent. The word "haplotype" is derived from the word "haploid," which describes cells with only one set of chromosomes, and from the word "genotype," which refers to the genetic makeup of an organism. A haplotype can describe a pair of genes inherited together from one parent on one chromosome, or it can describe all of the genes on a chromosome that were inherited together from a single parent. This group of genes was inherited together because of genetic linkage, or the phenomenon by which genes that are close to each other on the same chromosome are often inherited together. In addition, the term "haplotype" can also refer to the inheritance of a cluster of single nucleotide polymorphisms (SNPs), which are variations at single positions in the DNA sequence among individuals.
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You inherit one haplotype from each parent. Therefore, there are a total of four different haplotype combinations from 2 parents.
There is a basic rule in HLA inheritance. The rule is: you have a 25% chance of inheriting all of the same HLA (same 2 haplotypes) as any one of your siblings, you have a 25% chance of not inheriting any of the same HLA (none of the same haplotypes) and you have a 50% chance of sharing I haplotype with your siblings. Therefore, you have a 1 in 4 chance of being an identical match with your siblings.
B)there is no same HLA halotype of each of the three people involved in this case because the sister have no identical matching.
C) the brother of the patient is the match . Because the have 9 matching alleles. they have 47% PRA with brother.and 0% with sister.The probability of identifying an HLA-identical sibling donor depends only on the number of siblings ad is 44% for two.
D)no these are not acceptable results as they have not shown the HLA -C matching. These are incomplete results.